1. Field of the Invention
The present invention relates to transmission of multiframe in pre-procedure of facsimile.
Also, the present invention relates particularly to a facsimile apparatus having the function of transmitting a sub-address signal, a password signal, and a selective polling signal.
2. Related Background Art
Recently, a sub-address signal (SUB), a password signal (PWD), and a selective polling signal (SEP) have been added as standard signals in ITU-T Additional Recommendations.
In ITU Recommendations, at present, bit 47 in FIF of DIS/DTC is assigned to declaration of the presence or absence of a selective polling capability, bit 49 to declaration of the presence or absence of a sub-address capability, and bit 50 to declaration of the presence or absence of a password capability. In actuality, since the presence or absence of the capabilities can be indicated only by use of bits of DIS, bits 47, 49 and 50 of DTC are all set to "0". As for DCS, bits 47, 49, and 50 thereof are all set to "0".
In the present situation, the following three problems (1)-(3) are involved. The problems will be described with reference to FIGS. 47A to 48B.
(1) In FIG. 47A, first, a receiving station (called side) declares by DIS that it is ready to receive SEP, SUB, and PWD. In response to this, a transmitting station (calling side) sends PWD/SUB/DCS. When the receiving station has only received DCS properly (an error has occurred in transmission of PWD and SUB over a line), it determines that the transmitting station has issued neither PWD nor SUB (FIG. 47B).
Accordingly, the transmitting station sends image data according to transmitted PWD/SUB, while the receiving station performs a receiving process on the assumption that neither PWD nor SUB has been issued. This results in a transmission/reception error between the sending and receiving stations.
(2) In FIG. 48A, first a polling send station (called side) declares by DIS that it is ready to receive SEP, SUB, and PWD. In response to this, a polling receive station (calling side) sends PWD/SEP/DTC. When the polling receive station has only received DTC properly (an error has occurred in transmission of PWD and SEP over a line), it determines that the polling send station has issued neither PWD nor SEP (FIG. 48B).
Accordingly, the polling receive station performs a polling receive for image data according to transmitted PWD/SEP, while the polling send station performs a polling send process on the assumption that neither PWD nor SEP has been issued. This results in a transmission/reception error between the polling receive and send stations.
(3) ITU-T Additional Recommendations has decided to use bits 47, 49, and 50 of DTC for selective polling capability, sub-address capability, and password capability, respectively. However, their usage is not defined.
(4) Furthermore, for example, when a transmitting station sends an NSS signal and a DCS signal to determine a certain mode by the two signals and also when a receiving station receives the DCS signal only, the sending and receiving stations are different in a mode interpreted thereby. This has resulted in a drawback of an erroneous operation. For example, when standard and fine modes are determined by the DCS signal and also when a super fine mode is determined by the NSS signal, the sending and receiving stations are different in a line density interpreted thereby in the above case. This causes a trouble of the recording of an stretched image.